PWS is a congenital, progressive vascular malformation of the dermis. The pulsed dye laser can coagulate selectively PWS by inducing microthrombus formation within the targeted blood vessels. However, most patients requires multiple treatment and only a small proportion of patients obtain 100% fading of their PWS. The objective of the proposed research is the development of Optical Doppler Tomography (ODT) for application in the clinical management of patients with PWS by providing a semi-quantitative evaluation of the efficiency of pulsed laser therapy. The information provided by ODT on the depth, size, and density of the vasculatures will be used to select optimal pulse duration and light dosage of laser exposure for PWS therapy.